The invention describes a radiator thermostat to be fitted onto a radiator valve having a transmission element for transmitting a compressive force to the radiator valve, having an electric motor for driving the transmission element, having a control for the electric motor and having a power supply.
Radiator valves regulate the amount of heating fluid that flows through a radiator and thus the temperature in the room in which the radiator is located.
The radiator valve is, for example, fixedly disposed on the radiator or in a supply pipe. It is generally disposed in a corner connector that is located between the radiator pipe and the radiator. The valve has a valve seat and a valve disk that fits into the valve seat such that the through flow can be closed. A linear movement of the valve disk makes it possible to regulate the amount of through flow. The valve disk is connected to a linearly moveable guide unit, where a spring presses this guide unit, and thus the valve disk, away from the valve seat. The valve is then open in the neutral position.
A radiator valve control is fitted onto this radiator valve, where either a screw or snap-in connection may be provided. The radiator valve control has an actuator that interacts with the guide unit and thus with the valve disk and can move these parts. Since the valve disk is held open by the spring, the control need only exert a compressive force on the valve pin when the valve is to be closed.
A well-known radiator valve control is a radiator thermostat which has a temperature sensor, a temperature pre-selection means, a control and an actuator, the control then moving the actuator such that the temperature measured at the temperature sensor substantially corresponds to the pre-selected temperature.
This kind of radiator thermostat can have a purely mechanical construction. To this end, the thermostat has, for example, an expansion element and a transmission pin. The expansion element can be moved with respect to the valve using a knob, which makes it possible to pre-select the temperature. The expansion element changes its length in accordance with the temperature and thus exerts a compressive force via the transmission element on the valve pin.
However, the radiator thermostat may, for example, also be operated electrically. To this end, it has a temperature sensor that is connected to an electronic control unit. Moreover, there is an electric motor that is controlled by the electronic control unit and used to drive a transmission pin. The transmission pin is designed to exert a compressive force on the guide unit of the valve disk.
To pre-select the temperature, a control dial, for example, or a digital control having a display unit may be provided. This kind of electric thermostat generally has a battery or a rechargeable battery to supply it with power.
In order to close the radiator valve, it is necessary to move the transmission pin against the spring resistance of the radiator valve. Since the actuating force required for this is considerable, the electric motor needs a substantial amount of energy. In order to provide the high actuating force, gears are used that, in turn, have high frictional losses, which goes to additionally increase energy consumption.
The electronics also consume energy, although compared to the motor, this is marginal. This means that in the electric radiator thermostats currently found on the market, the batteries only last a few weeks. It is then necessary to change the batteries, which is both time consuming and costly, particularly if there are a large number of radiators.